Structure and ontogeny of Betula alleghaniensis – Pisolithus tinctorius ectomycorrhizae

1990 ◽  
Vol 68 (3) ◽  
pp. 579-593 ◽  
Author(s):  
H. B. Massicotte ◽  
R. L. Peterson ◽  
C. A. Ackerley ◽  
L. H. Melville
Keyword(s):  
Root Hairs ◽  
Root Surface ◽  
Pisolithus Tinctorius ◽  
Initial Contact ◽  
Broad Host Range ◽  
Betula Alleghaniensis ◽  
Cortical Cells ◽  
Structural Modifications ◽  
Hartig Net ◽  
Primary Roots

The ontogeny and ultrastructure of ectomycorrhizae synthesized between Betula alleghaniensis (yellow birch) and Pisolithus tinctorius, a broad host range fungus, were studied to determine the structural modifications in both symbionts during ectomycorrhiza establishment. A number of stages, including initial contact of hyphae with the root surface, early mantle formation, and mature mantle formation, were distinguished. Interactions between hyphae and root hairs were frequent. As a paraepidermal Hartig net developed, root epidermal cells elongated in a radial direction, but wall ingrowths were not formed. Repeated branching of Hartig net hyphae resulted in extensive fine branches and the compartmentalization of hyphal cytoplasm. Nuclei and elongated mitochondria were frequently located in the narrow cytoplasmic compartments, and [Formula: see text] thickenings developed along walls of cortical cells in primary roots.

Studies on the haustorium of Castilleja (Scrophulariaceae). I. The upper haustorium

1973 ◽  
Vol 51 (5) ◽  
pp. 917-922 ◽  
Author(s):  
David R. Dobbins ◽  
Job Kuijt
Keyword(s):  
Root Hairs ◽  
Surface Lipid ◽  
Electron Microscopic ◽  
Cortical Cells ◽  
Spherical Structure ◽  
Cortical Zone ◽  
Primary Roots ◽  
Distinct Cell ◽  
Parenchyma Cells ◽  
Host Tissues

The portion of the Castilleja secondary haustorium external to host tissues was investigated at the light- and electron-microscopic levels. One or more haustoria may be present along a single lateral root; however, primary roots of Castilleja may also have haustoria. A localized development of root hairs usually precedes haustorial formation. The first sign of haustorial formation is the swelling of root cortical cells which gives rise to a nearly spherical structure. Eventually, the haustorial epidermis is obliterated at the contact surface between parasite and host. The upper haustorium has a complex internal structure consisting of several distinct cell zones. The pericycle gives rise to a parenchymatous zone of cells adjacent to the plate xylem. Later, collenchyma differentiates in the center or core of the haustorium and is surrounded by a cortical zone of parenchyma cells. This is the first report of collenchyma tissue in a haustorium of any parasite. Thus, a mature Castilleja haustorium consists of a plate xylem zone, an adjacent parenchymatous zone, a centrally located collenchyma zone, and a peripheral cortical zone. The endophyte is initiated from hypodermal parenchymatous cells located between the collenchyma core and the haustorial surface. Lipid is abundant in the young endophyte and paramural bodies are common in many cells. Strands of vessel members differentiate at random and are sheathed by thin-walled densely cytoplasmic cells. Vessel members occur within the collenchyma zone as well, and frequently contain starch and other coarsely granular materials. No phloem was found in the upper haustorium of Castilleja. The upper haustorium of Castilleja and of other members of the Scrophulariaceae are compared.

Structure of ectomycorrhizae formed by Wilcoxina mikolae var. mikolae with Picea mariana and Betula alleghaniensis

1991 ◽  
Vol 69 (10) ◽  
pp. 2149-2157 ◽  
Author(s):  
Pamela F. Scales ◽  
R. L. Peterson
Keyword(s):  
Electron Microscopy ◽  
Picea Mariana ◽  
Lateral Roots ◽  
Root Apex ◽  
Root Surface ◽  
Betula Alleghaniensis ◽  
Oblique Angle ◽  
Hartig Net ◽  
Wilcoxina Mikolae ◽  
Scanning Electron

The structure of ectomycorrhizae synthesized between the E-strain fungus, Wilcoxina mikolae var. mikolae and two tree species, Picea mariana and Betula alleghaniensis, was characterized by light microscopy and scanning electron microscopy. For both mycorrhizal types, mantle formation was visible on lateral roots within 10 days of inoculation. Picea mariana ectomycorrhizae had a very thin mantle whereas B. alleghaniensis ectomycorrhizae had a mantle consisting of several layers. For both mycorrhizal types, the innermost mantle hyphae were embedded in a considerable amount of mucigel on the root surface. A well-developed Hartig net with labyrinthic growth occurred in both types of mycorrhizae. Betula alleghaniensis ectomycorrhizae had a paraepidermal Hartig net, and the root epidermal cells were radially elongate at an oblique angle. The Hartig net of P. mariana ectomycorrhizae penetrated the epidermis and all layers of the cortex. The cytoplasmic density of the intercellular hyphae was greatest towards the root apex. Ectomycorrhizal associations formed by E-strain fungi were similar to ectomycorrhizae formed by other fungi. Key words: E-strain, ectomycorrhizae, Wilcoxina, Picea, Betula, Hartig net.

Ontogeny of Alnus rubra – Alpova diplophloeus ectomycorrhizae. I. Light microscopy and scanning electron microscopy

1989 ◽  
Vol 67 (1) ◽  
pp. 191-200 ◽  
Author(s):  
H. B. Massicotte ◽  
R. L. Peterson ◽  
L. H. Melville
Keyword(s):  
Outer Layer ◽  
Lateral Root ◽  
Lateral Roots ◽  
Root Hairs ◽  
Fungal Colonization ◽  
Alnus Rubra ◽  
Cortical Cells ◽  
Lateral Root Primordia ◽  
Hartig Net ◽  
Fungal Hyphae

Ectomycorrhizae synthesized between Alpova diplophloeus and Alnus rubra are of two morphological types: one with a mantle formed along the entire length of the lateral roots and the other, the clavate type, with the mantle confined to the apical portion of the laterals. The morphology of the mycorrhiza is dependent on the stage of lateral root elongation at the time of colonization by fungal hyphae. Clavate mycorrhizae form on lateral roots that have already elongated at the time of fungal colonization. Fungal hyphae interact with root hairs at the base of clavate mycorrhizae. Mantles of both types are fairly compact with few extramatrical hyphae. Hartig net hyphae, which branch profusely primarily in the radial direction, are confined to the epidermis and midway along the radial walls of the outer layer of cortical cells. Second-order lateral root primordia are initiated in the mature Hartig net zone. Cells in the outer layer of the cortex of mycorrhizal roots collapse during fixation, indicating the possible presence of a barrier in the cell wall blocking the ingress of fixative.

Ontogeny of Eucalyptus pilularis – Pisolithus tinctorius ectomycorrhizae. I. Light microscopy and scanning electron microscopy

1987 ◽  
Vol 65 (9) ◽  
pp. 1927-1939 ◽  
Author(s):  
H. B. Massicotte ◽  
R. L. Peterson ◽  
A. E. Ashford
Keyword(s):  
Lateral Root ◽  
Lateral Roots ◽  
Ectomycorrhizal Fungus ◽  
Pisolithus Tinctorius ◽  
Broad Host Range ◽  
Lateral Root Development ◽  
First Order ◽  
Hartig Net ◽  
Ectomycorrhizal Roots ◽  
Eucalyptus Pilularis

Eucalyptus pilularis Sm. seedlings were grown in growth pouches and inoculated with the broad host range ectomycorrhizal fungus Pisolithus tinctorius (Pers.) Coker & Couch. External morphology and internal structure of all stages of ectomycorrhiza formation on first-order and second-order laterals were studied. The morphology of the ectomycorrhiza is dependent on the stage of lateral root development at the time of colonization by fungal hyphae. Emerging lateral roots are colonized by hyphae originating from the inner mantle of the parent root. The Hartig net does not spread internally from the parent root to the lateral root. All primary tissues of mycorrhizal lateral roots are differentiated close to the apical meristem. The epidermal cells undergo a marked increased in radial growth instead of the usual elongation in the axial plane. The hypodermis is a barrier to the penetration of hyphae so that Hartig net formation is paradermal only. Older portions of ectomycorrhizal roots show a degeneration of the epidermis, hypodermis, and cortex excluding the endodermis, and a proliferation of hyphae in these senescing tissues.

Root hair infection process and myconodule formation on Alnus incana by Penicillium nodositatum

1994 ◽  
Vol 72 (7) ◽  
pp. 955-962 ◽  
Author(s):  
Jeanine Sequerra ◽  
André Capellano ◽  
Monique Faure-Raynard ◽  
André Moiroud
Keyword(s):  
Root Hair ◽  
Light And Electron Microscopy ◽  
Root Hairs ◽  
Infection Process ◽  
Initial Contact ◽  
Alnus Incana ◽  
Cortical Cells ◽  
Infected Root ◽  
Root Hair Infection ◽  
Polysaccharide Matrix

Penicillium nodositatum infects the roots of alder trees and induces the formation of structures called myconodules, which are similar to young actinorhizae. Root infection of Alnus incana by P. nodositatum as well as myconodule development were studied by light and electron microscopy and observations were compared with those described for the infection by Frankia spp. We have established an obvious homology between the early steps of the infection caused by both microorganisms. The presence of the fungus near the roots induces deformation of root hairs. The infection site is probably localized in a folding of a deformed hair. As soon as hyphae penetrate into the hair, they become enclosed in a polysaccharide matrix. Initially, P. nodositatum colonizes a region near the infected root hair that may correspond to a slightly developed prenodule. Then a nodular primordium is initiated at some distance from the initial contact and the new nodular cortex is invaded by the fungus. The zone of infection is limited to the cortical cells by a barrier of tannins. Myconodules remain small and unilobed and have an outer morphology similar to that of an incompatible Frankia nodule. Key words: Alnus, myconodule formation, Penicillium, root hair infection.

Root-hair structure and development in the seagrass Halophila ovalis (R. Br.) Hook. F

1993 ◽  
Vol 44 (1) ◽  
pp. 85 ◽  
Author(s):  
DG Roberts
Keyword(s):  
Endoplasmic Reticulum ◽  
Nutrient Uptake ◽  
Root Hair ◽  
Root Hairs ◽  
Active Role ◽  
Root Surface ◽  
Cortical Cells ◽  
Golgi Bodies ◽  
Halophila Ovalis ◽  
Active Root

The seagrass Halophila ovalis normally produces one mature root, covered with a permanent mat of root hairs, per node. In this study, the development of the root hairs increased the effective root surface absorptive area by 215%. Of the root surface examined, 39% was devoted to root-hair production. Epidermal cells that produced root hairs contained more cytoplasm, endoplasmic reticulum and Golgi bodies than did adjacent hairless cells. In addition to appearing to be more metabolically active, root-hair-producing cells had a greater number of plasmodesmatal connections with the underlying outer cortical cells than did adjacent cells that did not produce root hairs. This would suggest that cells that produce root hairs play a more active role in nutrient uptake and exchange than do other cortical cells.

Characterization of the interaction between the dark septate fungus Phialocephala fortinii and Asparagus officinalis roots

2001 ◽  
Vol 47 (8) ◽  
pp. 741-753 ◽  
Author(s):  
T Yu ◽  
A Nassuth ◽  
R L Peterson
Keyword(s):  
Root Hairs ◽  
Root Surface ◽  
Epidermal Cells ◽  
Asparagus Officinalis ◽  
Structural Basis ◽  
Root Penetration ◽  
Root Tips ◽  
Cortical Cells ◽  
Phialocephala Fortinii

Phialocephala fortinii Wang & Wilcox is a member of root-inhabiting fungi known collectively as dark septate endophytes (DSE). Although very common and distributed worldwide, few studies have documented their interaction with roots on a structural basis. The objective of this study was to determine the early colonization events and formation of microsclerotia of P. fortinii in roots of Asparagus officinalis L., a species known to have DSE. A loose network of hyphae accumulated at the root surface, and coils formed around root hairs and external to epidermal cells overlying short cells of the dimorphic, suberized exodermis. Root penetration occurred via swollen, appressorium-like structures into epidermal cells where coiling of hyphae occurred along the periphery of the cells. Hyphae penetrated from the epidermis into short exodermal cells and from these into cortical cells. Hyphae colonized the cortex up to the endodermis and sometimes entered the vascular cylinder. Some root tips were colonized as well. Microsclerotia in epidermal and exodermal short cells accumulated glycogen, protein, and polyphosphate. Energy-dispersive X-ray spectroscopy on distinct bodies visible in microsclerotial hyphae revealed high levels of phosphorus.Key words: Mycelium radicis atrovirens, Phialocephala fortinii, microsclerotia, DSE.

Chemotaxis of zoospores of Phytophthora megasperma to primary roots of alfalfa seedlings

1978 ◽  
Vol 56 (7) ◽  
pp. 795-800 ◽  
Author(s):  
C. C. Chi ◽  
F. E. Sabo
Keyword(s):  
Trifolium Pratense ◽  
Primary Root ◽  
Root Hairs ◽  
Red Clover ◽  
Root Surface ◽  
Root Cap ◽  
Root Tips ◽  
Phytophthora Megasperma ◽  
Root Area ◽  
Primary Roots

Chemotaxis of the zoospores of Phytophthora megasperma was studied on freshly excised primary root tips of 2-day-old seedlings of nine alfalfa (Medicago sativa L.) cultivars and four other legume species. The highly susceptible cultivars Saranac, Algonquin, and Vernal attracted masses of zoospores within minutes after being placed into fresh zoospore suspensions. The moderately susceptible cultivars Iroquois, Angus, and Thor displayed less severe en masse zoospore accumulation. Resistant cultivars Apollo, Agate, and to a lesser degree WL-318 exhibited minor chemotaxis.Zoospores were strongly attracted to the region of elongation, immediately above the root cap area. Relatively few zoospores, if any, were attracted to the root cap and older regions of the roots. Zoospores were not attracted to root hairs. Within 0.5-1 h, zoospores attracted to the roots began to encyst and germinate. Germ tubes always originated from the side of cysts closest to the root surface, and all showed unidirectional growth towards the root.Very weak or no chemotactic responses of zoospores to nonhost legume plants of white sweet clover (Melilotus alba Desr.), red clover (Trifolium pratense L.), bird's-foot trefoil (Lotus corniculatus L.), and soybean (Glycine max (L.) Merr. cv. Vansoy) were observed. Roots of susceptible alfalfa seedlings pretreated in boiling water did not attract zoospores.Injured, susceptible alfalfa roots displayed a strong preferential attraction around a wounded root area. Varying zoospore densities occurred at different distances from the wound. Wounded, resistant alfalfa roots showed slightly more zoospore accumulation than the uninjured resistant roots.The magnitude of chemotaxis and response time appear to be related to the susceptibility or resistance of the young, primary roots of alfalfa seedlings.

Ectomycorrhizal and ectendomycorrhizal associations of Phialophorafinlandia with Pinusresinosa, Picearubens, and Betulaalleghaniensis

1987 ◽  
Vol 17 (8) ◽  
pp. 976-990 ◽  
Author(s):  
H. E. Wilcox ◽  
C. J. K. Wang
Keyword(s):  
Large Diameter ◽  
Root Surface ◽  
Epidermal Cells ◽  
Cortical Cells ◽  
Hartig Net ◽  
Mycorrhizal Associations ◽  
Intracellular Invasion ◽  
Inner Cortex ◽  
Root Axis ◽  
Distributed Clusters

Mycorrhizal associations formed by Phialophorafinlandia in Pinusresinosa were both ectomycorrhizal and ectendomycorrhizal with randomly distributed clusters of spherical hyphae within cells of the cortex. The ectomycorrhizal condition was common for short distances in the apices of short roots and in smaller diameter long roots, but intracellular invasion from the Hartig net occurred proximal to this zone, resulting in an ectendomycorrhizal structure. In large diameter long-root branches both conditions were found at different positions along the root axis. In addition, sclerotia-like inclusions occurred in the inner cortical cells, often radially opposite to the protoxylem. Mycorrhizal associations in Picearubens and Betulaalleghaniensis were predominantly ectomycorrhizal in all roots; sclerotial bodies could be present in the inner cortex of both hosts. The Hartig net extended to the endodermis in the spruce, but it surrounded only the epidermis in birch. The epidermal cells of birch ectendomycorrhizae elongated radially and obliquely to the root surface, but in spruce the mycorrhizal condition had no effect on radial dimensions of cortical cells.

A structural study of the interaction between the ectomycorrhizal fungus Pisolithus tinctorius and Pinus strobus roots

1983 ◽  
Vol 61 (4) ◽  
pp. 1185-1193 ◽  
Author(s):  
Y. Piché ◽  
R. L. Peterson ◽  
Melanie J. Howarth ◽  
J. André Fortin
Keyword(s):  
Light And Electron Microscopy ◽  
Cortical Cell ◽  
Middle Lamella ◽  
Pinus Strobus ◽  
Ectomycorrhizal Fungus ◽  
Pisolithus Tinctorius ◽  
Cortical Cells ◽  
Root Cells ◽  
Hartig Net ◽  
Limited Digestion

Stages in ectomycorrhizal development between the fungus Pisolithus tinctorius (Pers.) Coker & Couch and short roots of Pinus strobus L. were followed in growth pouches. Short roots from preinoculation through Hartig net formation were processed for light and electron microscopy. Fungal hyphae approaching the surface of roots have Thiéry-positive substances in their modified walls and in lomasomes, indicating the possibility of extracellular polysaccharide secretion. Hyphae grow between and beneath the flattened, tannin-filled superficial root cells and subsequently into the intercellular region of the cortex. A Hartig net several hyphae wide is formed, isolating the cortical cells from each other. Plasmodesmata were not observed in these cortical cells. Middle lamella material is always present around the intercellular hyphae, suggesting limited digestion by the hyphae. Cortical cell cytoplasm becomes necrotic in regions of mature Hartig net formation.

Sign in / Sign up

Export Citation Format

Share Document